1. Field of the Invention
The present invention relates to a semiconductor device, and particularly to a structure of a rewiring layer which is covered with an insulation film.
2. Description of the Related Art
The conventional semiconductor device has a structure in which a rewiring layer is formed on an interlayer insulation film of the lower layer (hereinafter, to be simply called a lower-layer interlayer insulation film), and the rewiring layer is covered with an interlayer insulation film of the upper layer (hereinafter, to be simply called an upper-layer interlayer insulation film) (for example, refer to Japanese Patent Laid-open Publication No. 2003-234429).
However, the rewiring layer which is formed of copper, or the like, and the interlayer insulation film which is formed of an oxide film, resin, or the like, differ in the physical properties, such as coefficients of their linear expansion, and the like. Therefore, with the structure in which the rewiring layer is simply covered with an upper-layer interlayer insulation film, interface peeling may occur between the rewiring layer and the interlayer insulation film when thermal stresses, or the like, are imposed thereon.
As the art to solve such a problem, there exists, for example, Japanese Patent Laid-open Publication No. 2003-124391 as described below. According to this Japanese Patent Laid-open Publication No. 2003-124391, the semiconductor device is provided with fine irregularities on the surface of the rewiring layer, and by these irregularities, improves the adhesive strength of the interface between the rewiring layer and the interlayer insulation film is improved.
However, the problem which is caused when thermal stresses, or the like, are imposed is not limited to the interface peeling at the adhesion surface between the rewiring layer and the interlayer insulation film. That is to say, with the conventional semiconductor device, when thermal stresses, or the like, are imposed thereon, the stresses are concentrated in the edge part in the vicinity of the rewiring layer. Therefore, there arise such problems as those of that, in the vicinity of this edge part, the rewiring layer and the interlayer insulation film peel off from each other, and that a crack is generated in the interlayer insulation film in the vicinity of the edge part.